1. Field of the Invention
The present invention relates generally to a semiconductor device, and more particularly to a semiconductor device with a conductive contact structure.
2. Description of the Prior Art
Along with the continuous miniaturization of the Integrated Circuits (IC), the feature size of each semiconductor device within the ICs also shrinks continuously. In order to overcome electrical or processing limitations arising from the miniaturization of semiconductor devices, semiconductor manufacturers have found out several solutions. For example, for a transistor device with a polysilicon gate, some disadvantages, such as boron penetration and depletion effect often occur and cause inferior performance of the transistor device. In order to solve these drawbacks, some semiconductor manufacturers adopt a gate-last process to replace the conventional polysilicon gate with a metal gate having metal electrode. Additionally, along with the shrinkage between two adjacent gate structures, semiconductor manufacturers also correspondingly invent a method for self-aligning a contact structure so as to overcome drawbacks due to the insufficient space between the two adjacent gate structures.
However, even though the above-mentioned semiconductor device adopts the metal gate and the self-aligned contact, there are still some technical problems need to be overcome. For example, when the space between two adjacent gate structures is less than a certain value, such as 10 nm, severe misalignment problems often happen during the process of fabricating self-aligned contacts, which leads to the lateral shift of the self-aligned contacts. Once the self-aligned contacts displaced from their predetermined positions, the contact areas between the self-aligned contacts and the underlying active regions are inevitably reduced. As a result, the contact resistance is increased.
Accordingly, in order to overcome the above-mentioned drawbacks, there is still a need to provide a modified structure having a metal gate and a self-aligned contact structure and a method thereof.